1. Field of the Invention
This invention relates to an electronic camera capable of setting an exposure value with or without selection of an exposure compensation by the preliminary exposure.
2. Description of the Related Art
The electronic camera using the image sensor such as CCD in recording pictures on the magnetic disc or the like has a narrower latitude to the quantity of light than the ordinary photographic camera using a silver-halide film and is, therefore, required to make exposures with a higher accuracy. In this respect, there have been many previous proposals. As disclosed in, for example, U.S. Pat. Nos. 4,523,101 and 4,734,777, prior to the main exposure, a preliminary exposure is made on the image sensor. Based on the level of the output signal for this time of the image sensor, the exposure value is compensated in controlling the main exposure. Also, the photographer of good experience sometimes favors the manual exposure mode where a proper exposure value can be obtained by manually controlling the exposure parameter setting means.
In the conventional electronic camera, however, the use of the capability of making the preliminary exposure always leads to occurrence of the compensation of the exposure value by the level of the preliminary output of the image sensor. Therefore, even when the photographer sets a desired exposure value by his hand as he considers it more suitable than the computed one, re-compensation by the preliminary exposure would take place, thus giving rise to a problem that the desired exposure control cannot be made.
Another problem of the above-described conventional example is that since every time a shot is to be taken, the preliminary exposure must be carried out and, after that, the main exposure occurs, the time gap from the moment at which the release button has been pushed down to the moment at which the actual picture is taken is very long. This is disadvantageous when achieving introduction of a capability of taking a series of continuous shots at a high frame rate into the camera.
Again, the image sensor has, despite large consumption of electrical energy, to be driven twice for every one picture, as has been described above. Therefore, the battery to be used must be of large capacity. This has been an obstacle for minimization of the size of the camera body.
The conventional camera in any photographic situation performs twice the opening-and-closing operation. In the case of a long exposure time, therefore, the successive two shutter sounds are heard discretely of each other, irritating the ear. In addition to this problem, there is another one in which the diaphragm has to be maintained stationary in the adjusted position for a long time.